A comprehensive investigation has been made of the solidification of nitrogen-atomized Al86Ni6Y4.5Co2La1.5, using focused ion beam, transmission electron microscopy, and other analytical means. Face-centered cubic Al2Y was identified to be the leading crystalline phase rather than crystalline Al. A new orthorhombic-structured phase was identified in partially or fully crystallized powder particles. Apart from oxygen, nitrogen was also found to be associated with the leading crystalline phase Al2Y in which nitrogen exists as substitutional Nx−. These findings facilitate the basis for understanding the unique aspects of the Al86Ni6Y4.5Co2La1.5 bulk metallic glass, including its powder preparation by gas atomization.